Persistent resource allocation

ABSTRACT

Methods and apparatus for communicating and utilizing persistent allocation of uplink resources are described herein. A base station can allocate persistent uplink resources to a client station, such that the resource allocation remains active for future uplink frames without the client station repeating a request for uplink resources or the base station expressly communicating the uplink resource allocation. A client station can request a persistent uplink resource allocation when wireless channel conditions are fairly consistent and not varying and the required uplink resources are predictably periodic and fixed in size. The base station can verify that the uplink resource request meets the criteria for persistent allocation and can allocate persistent uplink resources in a dedicated information element of an uplink resource map that is transmitted to the user. The resources allocated remain allocated to the client station in each frame satisfying a predetermined periodicity until deallocated.

CROSS-REFERENCES TO RELATED APPLICATIONS

The application claims the benefit of U.S. Provisional PatentApplication No. 60/971,526 filed Sep. 11, 2007 for “PERSISTENT UPLINKRESOURCE ALLOCATION”; and U.S. Provisional Patent Application No.61/013,622 filed Dec. 13, 2007 for “ERROR CORRECTION FOR A PERSISTENTRESOURCE ALLOCATION”; which are all incorporated herein by reference intheir entirety for all purposes.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The invention relates to the field of wireless communications. Moreparticularly, the invention relates to the field of resource allocationin a wireless communication system.

II. Description of Related Art

Wireless communication systems may support discontinuous transmission inwhich the various parties to a communication link use resources only asneeded. Limiting the allocation and consumption of resources to thosedevices actively engaged in communications increases the efficiency of awireless communication system. However, each device may need to requestan allocation of resources before it is granted the opportunity tocommunicate. The request and grant of communication resources can itselfconsume a large amount of resources that otherwise could be used tosupport additional users or provide increased bandwidth to active users.

It is desirable to minimize the amount of resources consumed inrequesting and granting resources for discontinuous communications.However, there remains the need to maximize the flexibility ingenerating access requests and allocating the resources associated withthe access requests.

BRIEF SUMMARY OF THE INVENTION

Methods and apparatus for communicating and utilizing persistentallocation of uplink resources are described herein. A base station canallocate persistent uplink resources to a client station, such that theresource allocation remains active for future uplink frames without theclient station repeating a request for uplink resources or the basestation expressly communicating the uplink resource allocation. A clientstation can request a persistent uplink resource allocation when therequired uplink resources are predictably periodic and fixed in size.The base station can verify that the uplink resource request meets thecriteria for persistent allocation and can allocate persistent uplinkresources in a n information element of an uplink resource map that istransmitted to the user. The resources allocated remain allocated to theclient station in each frame satisfying a predetermined periodicityuntil deallocated.

Among other things, described herein are methods and apparatuses forefficiently assigning persistent resources. In one aspect, when at leastone persistent allocations is made or updated, the base station sends aninformation element to a set of client stations. The information elementincludes a start allocation and a list of express grants of persistentallocations. The start allocation indicates a delineation between a setof previously assigned persistent allocations and a set of persistentand/or non-persistent allocations defined by the current informationelement. When received by a client station, the client station comparesthe start allocation with the starting point of its current persistentallocation. If the starting point is logically before the startallocation, the client station continues to operate according to thepreviously assigned persistent allocation. If its starting point islogically after the start allocation, the client station begins tooperate according any grant included within the current informationelement. In one aspect, the base station assigns resources to the clientstations in a logical order based upon the probability that the clientstation will incur an update to its persistent allocation.

In one aspect, the base station sends a first information elementspecifying a first, second and third persistent allocation for a first,second and third client station respectively, wherein the first, secondand third persistent allocations occur in numerical order in a logicalmapping. The base station may further determine a need for an update tothe second persistent allocation and, therefore, send a secondinformation element specifying a start location and a revised second andthird allocation, wherein the start allocation indicates a delineationwith the logical mapping between a set of previously assignedallocations and a set of allocations defined by the second informationelement.

A client station may receive a first information element specifying afirst persistent allocation occurring at a fixed point with a logicalmapping. It may also receive a second information element specifying astart allocation indicating a change point within the logical mapping.In addition, it may continue to operate according to the firstpersistent allocation if the fixed point occurs logically before thechange point. Otherwise, the client station operates according to anewly specified persistent allocation as indicated in the secondinformation element if the fixed point occurs logically after the changepoint. In another aspect, the client station ceases to operate accordingto the first persistent allocation if the fixed point occurs logicallyafter the change point and no new persistent allocation is includedwithin the second information element.

In one aspect, the base station has a persistent candidate processorconfigured to determine a set of client stations for which persistentresource are to be allocated in an upcoming frame. The base station mayinclude a group scheduler configured to determine a logical mapping forthe upcoming frame including an allocation for each client station inthe set of client stations. The base station can also include persistentuplink information element generator configured to determine a firstinformation element which includes an express allocation for each clientstation in the set of client stations which requires an updatedpersistent allocation and a start location within the logical mapping,wherein the start allocation indicates a delineation between a set ofpreviously assigned allocations and a set of allocations assigned by thefirst information element. The base station may also have a transmitteris configured to transmit the first information element to a pluralityof client stations.

In another aspect, the client station has a receiver configured toreceive a first and second information element and an uplink map moduleconfigured to determine whether the first information element specifiesa first persistent allocation occurring at a fixed point with a logicalmapping. The client station also has a storage device for storinginformation concerning the first persistent allocation. The uplink mapmodule determines whether the second information element specifies astart allocation indicating a change point within the logical mappingand instructs an uplink resource mapper to continue to operate accordingto the first persistent allocation if the fixed point occurs logicallybefore the change point.

The base station, according to an optional feature, determines a rate ofchange factor for each one of a set of client stations to determine alogical mapping for grant of persistent allocations for the set ofclient stations based at least in part on the rate of change factor. Thebase station orders the persistent allocations such that a first clientstation with a lower rate of change factor is scheduled logically beforea second client station with a higher rate of change factor. The basestation's determination of the rate of change factor may be based atleast in part on one or more factors including a mobility factor, amodulation and coding scheme, a voice activity factor and a channelquality indication.

A base station has, in one embodiment, a persistent candidate processorconfigured to determine a set of client stations for which persistentresource are to be allocated in an upcoming frame and a group schedulerconfigured to determine a logical mapping for the upcoming frameincluding an allocation for each client station in the set of clientstations, wherein the logical mapping is based at least in part on arate of change factor associated with each client station in the set ofclient stations.

The client station receives, in one embodiment, a first informationelement specifying a first persistent allocation occurring at a fixedpoint with a logical mapping, The client station then receives a secondinformation element including a mask. The client station continues tooperate according to the first persistent allocation if the maskindicates that the first persistent allocation has not been deallocatedand that no persistent allocation occurring logically earlier than thefirst persistent allocation has been deallocated. In some embodimentsthe second information element includes an indication of the magnitudeof a deallocated persistent allocation. The client station determines anew persistent allocation if a second persistent allocation occurringlogically earlier than the first persistent allocation has beendeallocated. The client station further may shift the first persistentallocation logically earlier according to a magnitude of the secondpersistent allocation. In one aspect, the second information elementspecifies the magnitude of the second persistent allocation.

According to an optional feature, the base station sends one or moreinformation elements specifying a first, second and third persistentallocation for a first, second and third client station respectively,wherein the first, second and third persistent allocations occur innumerical order in a logical mapping. The base station later sends asubsequent information element using a mask to commanding that thesecond client station cease operation on the second persistentallocation.

Certain additional means for implementing all of these aspects are alsodisclosed. Many aspects may be stored in a computer-readable medium.Additional aspects of the invention are detailed in the descriptionprovided herein and associated figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of embodiments of the disclosurewill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings, in which like elements bearlike reference numerals.

FIG. 1 is a simplified functional block diagram of an embodiment of awireless communication system.

FIG. 2 is a simplified functional block diagram of an embodiment of abase station implementing persistent uplink resource allocation.

FIG. 3 is a simplified functional block diagram of an embodiment of aclient station configured to operate using persistent uplink resourceallocation.

FIG. 4 is a simplified flowchart of an embodiment of a method ofpersistent uplink resource allocation.

FIG. 5 is a simplified flowchart of an embodiment of a method ofoperating with persistent uplink resource allocation.

FIG. 6 is a simplified embodiment of an uplink frame.

FIG. 7 is a simplified representation of a logical mapping of an uplinkresource allocation.

FIGS. 8A-8B are simplified embodiments of uplink frames illustratingpartial persistent resource reallocation.

FIG. 9 is a simplified flowchart of an aspect of a method of efficientlyassigning a persistent resource allocation.

FIG. 10 is a simplified flowchart of an aspect of a method of generatinga persistent uplink allocation information element.

FIG. 11 is a simplified diagram showing a series of persistentallocation regions of a downlink frame and illustrating use of a mask.

FIG. 12 is a simplified flowchart of an aspect of a method ofdeallocating a persistent resource allocation using a mask from theperspective of a base station.

FIG. 13 is a simplified flowchart of an aspect of a method ofdeallocating a persistent allocation resource using a mask from theperspective of a client station.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A base station in a wireless communication system can implementpersistent uplink resource allocation (also known as a stickyallocation) to reduce the signal bandwidth and processing associatedwith receiving an uplink resource request from a client station,determining the proper resource allocation, scheduling the resourceallocation, and communicating the resource allocation to the requestingclient station.

When the base station assigns a standard non-persistent downlink oruplink allocation for use by a client station, the allocation is validfor a predetermined frame, such as a frame in which the allocation isgranted or the frame following the frame in which the allocation isgranted, depending on the allocation relevancy. In contrast, when a basestation assigns a persistent downlink or uplink allocation to a clientstation, the allocation typically remains valid for multiple futuredownlink or uplink frames. Thus, the client station does not need torepeat a request for uplink resources periodically over a long series offrames. Nor does the base station need to expressly and repeatedlyidentify a downlink or uplink resource allocation in a series ofdownlink or uplink map information element (IE) messages.

A client station typically requests a persistent downlink or uplinkallocation when the client station is producing a constant orpredictable data stream such as one which is predictably periodic and inwhich the packets are generally fixed in size. For example, when aclient station has established a voice over Internet protocol (VoIP)connection, a steady stream of voice packets will typically be produced.The base station can verify that the downlink or uplink resource requestmeets the criteria for persistent resource allocation and allocatepersistent downlink or uplink resources as part of a persistent downlinkor uplink map information element (IE) message that is transmitted tothe client stations in the system.

In addition, the base station may have the ability to determine that aclient station is a candidate for a persistent downlink or uplinkresource allocation. For example, the base station can determine that aclient station is a candidate for a persistent downlink or uplinkresource allocation based on one or more parameters. The parameters caninclude, for example, repeated requests for uplink resource allocationsfrom the client station, the consistency of the resource allocationrequested, stability of characteristics of a wireless channel betweenthe base station and the client station, knowledge of the packet arrivaldistribution, and the type of connection. As an example, if theconnection is in support of VoIP communication, the base stationtypically knows that the packet arrival pattern is a good candidate forpersistent resource allocation.

The persistent allocation remains dedicated to the client station infuture frames until a predetermined terminating event, such as a passageof time, passage of a predetermined number of frames, the base stationnotifying the client station that the resource has been changed ordeallocated, a base station reallocating all or part of resourcesallocated to another client station, and the like or some combinationthereof. The base station may deallocate a persistent resource bysending a revised persistent downlink or uplink map IE which no longerallocates a persistent resource to the client station or reallocatespersistent resources to the client station. In one aspect, the basestation sends an express deallocation message.

The base station can group the client station resource request andresource allocation to any one of multiple persistence groups. The basestation can select a persistence group for a particular client stationbased on such factors as a traffic arrival pattern, a power class of theclient station, load balancing at the base station, and the like or somecombination thereof.

The base station can allocate resources to the client stations in eachof the persistence groups such that members of each persistence grouptransmit in a frame distinct from any other persistence group.Similarly, the base station can allocate persistent resources to theclient stations in each of the persistence groups such that members ofeach persistence group receive in a frame distinct from any otherpersistence group.

For example, each persistence group can be associated with a group cyclenumber and a persistent resource allocation can be valid for framesassociated with the group cycle index. In one embodiment, thepersistence groups can be time cycled in a round-robin schedule in orderto provide uniform access and a uniform rate across the multiplepersistence groups. A simple implementation utilizes the frame numberand group cycle index to identify the active persistence groupassociated with a particular frame. The active persistence group can beidentified by determining the modulo function of the frame number andthe total number of persistence groups, typically notated as MOD (framenumber, N), and comparing the result against the group cycle index,where N represents the number of persistence groups. (The modulooperation returns the remainder of division of one number by another.Given two numbers, a (the dividend) and x (the divisor), mod (a,x) isthe remainder of division of a by x. For instance, the expression MOD(7,3) would evaluate to 1, while MOD (9,3) would evaluate to 0.)

The client station need not have any knowledge of its group cycle indexand only needs to know the number of persistence groups, N. The clientstation can determine its group cycle index by determining the value ofMOD (frame number, N) for the first frame number for which it isallocated persistent downlink or uplink resources. Groups may also beidentified and associated with client stations explicitly bycommunicating a period parameter in the persistent allocation IE.

In other aspects, the persistence groups can be predetermined based onan algorithm which is less periodic than the modulo aspect describedabove. For example, the persistence groups could be determined based ona pseudo random pattern. In yet other aspects, periodic, pseudo randomand other means of forming persistence groups may be used.

In a typical Orthogonal Frequency Division Multiple Access (OFDMA)system, the base station can distinguish data coming from the variousclient stations according to time (number of symbols) and frequency(number of subcarriers). Of course in other systems, the base stationmay distinguish data coming from the various client stations accordingto some other physical layer (PHY) characteristics associated with thesystem.

To reduce overhead, the base station typically does not assignindividual physical layer units to the client stations. Instead, thephysical layer units are grouped together into “allocation units.” Thebase station assigns resources to the client stations by specifying oneor more allocation units, rather than designating individual physicallayer units. An allocation unit can be, for example, a combination of apredetermined number of subcarriers and symbols. In one embodiment, aminimum allocation unit is referred to as a “slot,” and a slotencompasses a predetermined number of subcarriers in one or more OFDMAsymbols.

According to IEEE 802.16, communication on both the uplink in thedownlink are divided into frames of fixed a length. Each frame includesa downlink subframe and uplink subframe. The downlink subframe typicallyincludes link management transmissions (such as synchronization signalsand the like), overhead channels (such as the fast feedback channelsdiscussed below), a number of downlink allocation units for carryinguser data from the base station to the client stations as well as othertypes of overhead and data transmissions. The uplink subframe includesmany of the same categories of transmissions, including uplinkallocation units for carrying user data from the client station to thebase station and control signaling channels for system control,administration and the like.

Modulation is the process of encoding information onto a signal fortransmission. Many modulation schemes are well known in the artincluding binary phased shift keying (BPSK), quadrature phase shiftkeying (QPSK) and quadrature amplitude modulation (QAM.) Modulationschemes differ from one another according to the amount of data carriedby any one symbol. Higher order modulation schemes carry more data persymbol. For example, a 16 QAM symbol carries 4 bits of data per symbolwhile BPSK modulation carries only one bit of data per symbol.

Higher order modulation schemes are more susceptible to channelconditions than lower order modulation schemes. Thus, use of a higherorder modulation scheme is more likely to result in errors than use of alower order modulation scheme under poor channel conditions.

However higher order modulation schemes are more efficient in terms ofthe amount of information that can be transferred over the wireless linkin a fixed period of time. Thus, within a fixed period of time, moredata can be transferred over the link using a higher order modulationscheme than a lower order modulation scheme if channel conditions aregood. Thus, transmissions using lower order modulation schemes are morerobust, but less efficient, and transmissions using higher ordermodulation schemes are less robust but more efficient.

In order to improve the performance of the wireless link, errorcorrection coding, such as forward error correction (FEC), can beapplied at the transmitter. Using complex error correction schemes, sometype of redundancy is introduced in the data before transmission. Thecode rate typically refers to the length of the uncoded informationdivided by the length of the resulting encoded information. Theredundancy can be used to correct for errors which are introduced by thewireless channel. The effectiveness of a coding scheme is measured interms of coding gain, which can be expressed as the difference betweenthe signal to noise level required to reach the same bit error ratelevel for encoded and uncoded data. Modern error correction codingtechniques provide substantial coding gains. However, due to theredundancy introduced, the use of error correction coding typicallydecreases the effective rate at which data is transmitted over thechannel. Therefore, transmissions using codes having higher redundancyrates are more robust, but less efficient than, transmissions usingcodes having lower redundancy rates.

The IEEE 802.16e standard and its progeny define a variety of modulationand coding scheme (MCS) combinations. The MCS specifies a type ofmodulation as well as a type of forward error correction which theclient station will use on uplink transmissions. The MCS combinationsaccommodate the large variation in performance associated with theclient stations scattered throughout the coverage area. Proper selectionof an MCS combination is important to both the efficiency andperformance of a wireless link.

When the base station assigns an allocation unit to a specific clientstation, it also specifies the MCS combination to be used on theallocation, whether persistent and non-persistent resource allocations.

Once the base station sends a persistent resource allocation, generallyit need not resend the resource allocation unless a change to thedownlink or uplink resource allocations makes it advantageous to resendthe resource allocation. For example, a new full or partial persistentuplink map IE may be sent when there is a need to change the size of theallocation. Such a size change may occur if the operating conditions ofthe client station assigned a persistent allocation are altered orotherwise change to such a degree that use of a new MCS combination isadvantageous. Among other reasons, the base station typically resendsthe persistent downlink or uplink map IE to identify the new MCScombination and to assign the client station fewer or more allocationunits as appropriate. In addition, a new persistent downlink or uplinkmap IE may be sent when a voice activity state changes, thus changingthe rate of occurrence of the persistent allocation. In addition thebase station typically resends the persistent uplink map IE if requestedby the client station to do so, and may alter a persistent mapaccordingly. Of course, the base station can be configured toperiodically resend the persistent downlink or uplink map IE even if nochanges have occurred to permit client stations in the base stationcoverage area to verify the persistent downlink and uplink resourceallocations. In addition, there may be several other instances in whichpersistent downlink and uplink map IE are resent, some of which arediscussed below.

The descriptions contained herein generally focus on OFDMA wirelesscommunication systems, and particularly are directed towards IEEE 802.16wireless communication systems or wireless communication systems basedon IEEE 802.16e as modified or otherwise extended or enhanced by themethods and apparatus described herein. However, the implementation ofpersistent downlink or uplink resource allocation scheme in an IEEE802.16e system is used merely as an example. The use of a persistentdownlink or uplink resource allocation scheme can be implemented invirtually any type of wired or wireless communication system.

In one aspect, the base station can be configured to just update theportion of the persistent uplink resource allocation information thatfollows the persistent resource allocation information that changes. Thepersistent resource allocation information occurring prior to the changeneed not be resent.

A client station that is allocated a persistent uplink resource can alsoexperience reduced processing. The client station can request apersistent allocation or otherwise receive a persistent resourceallocation from the base station in response to a resource request. Theclient station can determine the group cycle index for the persistentallocation in order to identify the frames for which its resourceallocation are valid. The client station can continue to use theresource allocation until communications are completed, the clientstation requests a change, or the base station notifies the clientstation of a resource allocation update.

The client station can store a newly received persistent resourceallocation information element allocating the persistent uplinkresources. The client station can compare the new persistent resourceallocation information element to the stored state to determine if itsresource allocation has changed.

For example, if the client station determines that a resource allocationmap includes no persistent uplink resource allocations, then the clientstation may determine that no changes have occurred. If the clientstation receives persistent resource allocation information, it cancompare some or all of the received information against the stored stateto determine if its resource allocation has been temporarily orpermanently reallocated.

FIG. 1 is a simplified functional block diagram of an embodiment of awireless communication system 100. The wireless communication system 100includes a plurality of base stations 110 a, 110 b, each supporting acorresponding service or coverage area 112 a, 112 b. Each base station110 a and 110 b can be coupled to a network (not shown) such as a wirednetwork, and can be configured to allow wireless communication withdevices on the wired network.

A base station, for example 110 a, can communicate with wireless deviceswithin its coverage area 112 a. For example, the first base station 110a can wirelessly communicate with a first client station 130 a and asecond client station 130 b within the coverage area 112 a over adownlink 116 a and an uplink 116 b. In another example, the first clientstation 130 a can communicate with a remote device (not shown) via thefirst base station 110 a. The downlink is a path from the base stationto the client station. The uplink is the path from the client station130 be to the base station.

The base stations, 110 a and 110 b, can be part of the samecommunication network or can be part of distinct communicationsnetworks. The base stations 110 a and 110 b can be in communication witheach other, either through a direct communication link or via anintermediary network. Alternatively, where the base stations 110 a and110 b are in distinct networks, a first base station 110 a may have noknowledge regarding the operation of the second base station 110 b.

Although for simplicity only two base stations are shown in FIG. 1, atypical wireless communication system 100 includes a much larger numberof base stations. The base stations 110 a and 110 b can be configured ascellular base station transceiver subsystems, gateways, access points,radio frequency (RF) repeaters, frame repeaters, nodes or any wirelessnetwork entry point.

Although only two client stations 130 a and 130 b are shown in thewireless communication system 100, typical systems are configured tosupport a large number of client stations. The client stations 130 a and130 b can be mobile, nomadic or stationary units. The client stations130 a and 130 b are often referred to as, for example, mobile stations,mobile units, subscribers, subscriber units, client stations, userdevices, wireless terminals or the like. A client station can be, forexample, a wireless handheld device, a vehicle mounted device, aportable device, client premise equipment, a fixed location device, awireless plug-in accessory or the like. In some cases, a client stationcan take the form of a handheld computer, notebook computer, wirelesstelephone, personal digital assistant, wireless email device, personalmedia player, meter reading equipment or the like and may include adisplay mechanism, microphone, speaker and memory.

In one example, the wireless communication system 100 is configured forOFDMA communications. For example, the wireless communication system 100can be configured to substantially comply with a standard systemspecification, such as IEEE 802.16e or some other wireless standard. Inone aspect, the wireless communication system 100 can support thepersistent downlink or uplink resource allocation described herein as anextension or enhancement to the system standard or as part of a systemstandard.

The wireless communication system 100 is not limited to an OFDMA system,and use of persistent uplink resource allocation described herein is notlimited to application in OFDMA systems. The description is offered forthe purposes of providing a particular example of the operation ofpersistent uplink resource allocation in a wireless communicationenvironment.

The base stations 110 a and 110 b are configured to transmit datapackets to the client stations 130 a and 130 b organized in frames. Eachframe can include a number of allocation units.

Each base station, for example 110 a, can supervise and control thecommunications within its respective coverage area 112 a. Each activeclient station, for example 130 a, registers with the base station 110 aupon entry into the coverage area 112 a. The client station 130 a cannotify the base station 110 a of its presence upon entry into thecoverage area 112 a, and the base station 110 a can interrogate theclient station 130 a to determine the capabilities of the client station130 a.

The base station 110 a assigns one or more temporary identifiers to theclient station 130 a for use in identifying the client station 130 a tothe base station 110 a. The temporary identifier can be referred to as aConnection Identifier (CID). The system can allocate a predeterminedrange of numbers or characters for the CID, and reserves a number ofbits necessary to support the maximum CID value in each messagerequiring a CID value. In many systems, a client station may establishmore than one connection and be associated with a plurality of CIDvalues. For example, if a handheld device is both surfing the Internetand participating in a voice over IP call, each of the connections maybe assigned an individual CID value. Thus, although for simplicity sakea persistent allocation is typically referred to herein as assigned to aparticular client station, in many systems, the persistent allocationsare assigned per connection rather than per client station.

In a packet based wireless communication system 100, it may beadvantageous for the system to allocate resources as needed, rather thanmaintaining an active channel assignment for each client station 130 aor 130 b having an established communication session with a base station110 a or 110 b. The base station 110 a can allocate resources to theclient station 130 a on an as needed basis. For example, in an OFDMAsystem, the base station 110 a can allocate time and frequency resourcesto each client station 130 a when the client station 130 a hasinformation to send to the base station 110 a.

The client stations 130 a and 130 b can notify the serving base station,for example, 110 a, when the client stations 130 a and 130 b arereporting information to the base station 110 a or when the clientstations 130 a and 130 b request uplink resources. Each base station,for example 110 a, can allocate some resources to support a randomaccess channel (RAC), dedicated control channel or other signaling pathused by the client stations 130 a and 130 b to report or requestresources.

The base station 110 a can periodically allocate resources to supportthe random access channel. In one embodiment, the base station 110 a cansupport a random access channel in each uplink frame. For example, abase station 110 a can allocate a portion of the uplink to a randomaccess channel. The base station 110 a can allocate, for example, atime, duration, and number of OFDM subcarriers on the uplink portion forthe random access channel. Each of the random access channel parametersmay be static or may be dynamic. The base station 110 a can include therandom access channel allocation information in a downlink portion thatis broadcast across its associated coverage area 112 a.

The client station 130 a may transmit a bandwidth request to the basestation 110 a using the random access channel, a dedicated controlchannel, piggyback messaging, in band messaging or other signaling path.In response to the request, the base station 110 a may allocate uplinkresources to the client station 130 a.

The wireless communication system 100 can eliminate the need for acontinual request and grant of resources by utilizing persistent uplinkresource allocations. A client station, e.g. 130 a, may request apersistent resource allocation or a base station, e.g. 110 a maydetermine that a client station 130 a is a candidate for a persistentresource allocation.

For example, a first client station 130 a may be engaged in burstytransmissions, require limited uplink resources, communicate latencyinsensitive transmissions, or may otherwise not be a candidate for apersistent resource allocation. Additionally, a rapidly changingwireless channel between the first client station 130 a and the basestation 110 a, for example, due to mobility, may make the uplinkcommunications from the first client station 130 a less conducive topersistent resource allocations.

In contrast, a second client station 130 b may be relatively stationary,or otherwise may have relatively constant wireless channelcharacteristics. Additionally, the second client station 130 a maydesire to support regular, latency sensitive communications over theuplink, such as when supporting voice over IP (VoIP). The base station110 a may recognize that the second client station 130 b is a bettercandidate for persistent uplink resource allocation, and may thereforeallocate persistent uplink resources to the second client station 130 b.The base station may allocate an uplink persistent allocation, downlinkpersistent allocation or both.

FIG. 2 is a simplified functional block diagram of an embodiment of abase station 200 implementing persistent uplink resource allocation. Thebase station 200 can be, for example, one of the base stations in thewireless communication system of FIG. 1.

The base station 200 includes an antenna 202 that can be coupled to areceiver 210 and transmitter 280 within the base station 200. AlthoughFIG. 2 illustrates a single antenna 202, the antenna 202 can be one ormore antennas configured to support multiple transmit and receiveoperating bands, multiple input, multiple output (MIMO) operation, beamsteering, spatial diversity and the like. If the base station 200supports frequency division multiplexing of the transmit and receivebands, the base station 200 can include a duplexor (not shown) toisolate the transmit signals from the receiver 210. The receiver 210 andtransmitter 280 can be distinct or can be part of a transceiver.

The receiver 210 is configured to receive the uplink transmissionstransmitted by a client station (not shown), such as one of the clientstations of FIG. 1. Initially, a client station can synchronize andregister with a base station 200 once the client station enters acoverage area of the base station 200 or upon waking up from a sleep oridle state. The receiver 210 can receive a request for uplink resourcesin a request from a client station transmitted over a random accesschannel, a fast feedback channel, piggybacked data channel, in bandmessaging or any other type of control signaling channel. A controlsignaling channel processor 220 is coupled to the receiver 210 andoperates to determine the presence of an uplink allocation request. Thecontrol signaling channel processor 220 may also perform associatedduties in combination with one or more functional modules to identifythe requesting client station and to identify the nature and size of theresource allocation request. For example, the control signaling channelprocessor 220 may operate in conjunction with a downlink signalprocessor 270 to communicate additional information to the clientstation that enables the client station to communicate the additionalbandwidth, nature, and identity information.

A persistent candidate processor 230 can process the uplink resourceallocation request, for example, processed by the control signalingchannel processor 220 to determine whether the requesting client stationis a good candidate for persistent resource allocation. The persistentcandidate processor 230 can, for example, determine an express requestfor a persistent channel or may monitor one or more parameters todetermine whether the client station is a candidate for persistentresource allocation. In addition, the persistent candidate processor 230can receive a persistent request from another element of the basestation or other infrastructure element.

The persistent candidate processor 230 may also monitor the receivedsignal to determine a channel characteristic associated with therequesting client station. Alternatively, the persistent candidateprocessor 230 may monitor the received signal for feedback informationfrom the client station characterizing its channel characteristics. Suchsignaling may be processed by the control signaling channel processor220.

The persistent candidate processor 230 can be coupled to a groupscheduler 240 and to a uplink MAP generator 260. If the persistentcandidate processor 230 determines that the resource request and clientstation are not candidates for persistent allocation, the persistentcandidate processor 230 can signal the UL MAP generator 260 to generatea non-persistent uplink resource allocation.

If the persistent candidate processor 230 determines that the resourcerequest and client station are good candidates for persistentallocation, the persistent candidate processor 230 can communicate theinformation to the group scheduler 240. The group scheduler 240 can beconfigured to schedule persistent allocations to one or more groups froma predetermined number of groups. The group scheduler 240 can determinethe group or groups based on a variety of parameters and metrics. Forexample, the group scheduler 240 can attempt to balance persistentallocations across each of the groups or may operate to optimize someother constraint or metric.

The group scheduler 240 can communicate the group information to apersistent UL Information Element (IE) generator 250 that operates togenerate the persistent UL allocation IE for the group, including theallocation for the requesting client station. As further describedbelow, group scheduler 240 and persistent UL IE generator 250 may alsoperform functions related to the start allocation information elementand the determination of a logical order of the persistent allocations.

The persistent UL IE generator 250 can communicate the persistent ULallocation IE to the UL-MAP generator 260 for inclusion in the UL-MAP.The UL-MAP generator 260 can be configured to generate the UL-MAPincluding any persistent and non-persistent UL allocations.

The UL-MAP generator 260 couples the UL-MAP information element to thedownlink signal processor 270 which creates the final message fortransmission over the downlink. The downlink information can be coupledto the transmitter 280 for broadcast across the coverage area supportedby the base station 200.

FIG. 3 is a simplified functional block diagram of an embodiment of aclient station 300 configured to operate using persistent uplinkresource allocation. The client station 300 can be, for example, one ofthe client stations illustrated in the wireless system of FIG. 1.

The client station 300 can include an antenna 302 coupled to a receiver310 and a transmitter 370. Although a single antenna 302 is shown asshared between a transmitter 370 and receiver 310, multiple antennas canbe used.

The receiver 310 can be configured to operate to receive the downlinktransmissions from a base station such as the base station of FIG. 2. AUL MAP module 320 coupled to the receiver 310 can be configured toextract the UL-MAP information element from the downlink signal.

The UL-MAP module 320 can be configured to examine the UL-MAPinformation element to determine whether the client station 300 has beengranted uplink resources, and if so, whether the allocation ispersistent or non-persistent.

If the UL-MAP module 320 determines that the UL MAP information elementindicates a persistent resource allocation for the client station, theUL-MAP module 320 can store the persistent UL allocation informationelement in a storage device 324. The UL-MAP module 320 can alsocommunicate a persistent UL allocation to a group cycle index module 340that is configured to determine the group cycle index associated withthe UL resource allocation. The group cycle index module 340 cancommunicate the group cycle index value to a synchronizer 360 to permitthe synchronizer 360 to synchronize the UL transmissions to the properframes.

The UL-MAP module 320 can also communicate the persistent UL-MAPinformation to a UL resource mapper 330. The UL resource mapper 330 canbe configured to compare the current persistent allocation map againstthe stored persistence map from the storage device 324 to determine theactual UL resources allocated to the client station 300. The UL MAPmodule 320 may use the storage device 324 to perform functions relatedto receipt and processing of a start allocation information element.

For example, the UL resource mapper 330 determines whether the startallocation information element occurs logically before or after apreviously assigned persistent allocation stored in storage device 324.When the start allocation occurs logically before the previouslyassigned persistent allocation, the UL resource mapper 330 determines anew allocation or deallocation with reference express informationcontains in the UL-MAP information element. When the start allocationoccurs logically after the previously assigned persistent allocation,the UL resource mapper 330 determines that operation should proceedaccording to the previously assigned allocation.

The UL resource mapper 330 maps the uplink information to the properresources in a channelizer 350 based on the resource allocation. Forexample, the UL resource mapper 330 can be configured to control thesubcarriers and symbols that UL information is mapped to in thechannelizer 350.

The output from the channelizer 350, which can be, for example, a seriesof OFDM symbols, is coupled to the synchronizer 360 that can beconfigured to synchronize the symbol timing to the timing of the framesin which the uplink resource is allocated. The output of thesynchronizer 360 is coupled to a transmitter 370 that can be configuredto upconvert the signal to a desired operating frequency beforetransmitting it using the antenna 302.

FIG. 4 is a simplified flowchart of an embodiment of a method 400 ofpersistent uplink resource allocation. The method 400 can be performed,for example, by the base stations of FIG. 1 or the base station of FIG.2 to implement persistent uplink resource allocation.

The method 400 begins at block 410 when the base station receives aresource request. In one aspect, the request is received via the antenna202, the receiver 210 and the control signaling channel processor 220 ofFIG. 2. In one aspect, another element of the base station or otherinfrastructure elements determines a persistent allocation may beappropriate.

The base station proceeds to block 420 and determines if the connectionis suitable for a persistent resource allocation. In one aspect, thepersistent candidate processor 230 of FIG. 2 performs these functions.

The base station proceeds to block 430 and determines whether there areany existing persistent resource allocations. For example, thepersistent candidate processor 230 makes this determination withreference to information stored an associated memory. At block 440, thebase station schedules the client station and persistent resourceallocation to one or more of a predetermined plurality of groups, whereeach group defines a set of persistent resource allocations. In oneaspect, with respect to block 440, one or more elements within the basestation, such as the group scheduler 240 shown in FIG. 2, schedules thepersistent allocation in a logical order based on a probability that theclient station will experience a change to its persistent allocation, asdescribed further below.

The base station proceeds to block 450 and generates a persistent uplinkallocation information element for the group having the resourceallocation for the client station. The uplink allocation informationelement can be a complete persistent resource allocation refreshing allpersistent resource allocations within the group or can be a partialresource allocation that identifies a subset of the persistent resourceallocations in the group. In one aspect, in block 450, the base stationalso determines a start allocation information element as furtherdescribed below which allows to transmit only a partial update. In oneaspect, the functions of block 450 are performed by group scheduler 240,persistent UL IE generator 250 and UL MAP generator 260.

The base station proceeds to block 460 and transmits the uplink resourceallocation information element within a downlink transmission. Forexample, the base station can be configured to include the uplinkpersistent resource allocation information element as part of the UL-MAPtransmitted in the downlink signal. In one aspect, the functions ofblock 460 are performed via 230 the downlink signal processor 270, thetransmitter 280 and the antenna 202. After transmitting the mapinformation, the base station is done for the frame of information.

FIG. 10 is a simplified flowchart of an aspect of a method 1000 ofgranting persistent allocations, further illustrating operationaccording to FIG. 4. In block 1010, the base station sends aninformation element which assigns persistent allocations to a connectionassociated with client stations CS1, CS2 . . . CS6. In addition the basestation may assign non-persistent allocations to one or more clientstations. For purposes of example, it is assumed that the informationelement specifies that the persistent allocations occur within a logicalmapping in numerical order from client station CS1 to client stationCS6. Referring back to FIG. 4, block 1010 may represents a first passthrough FIG. 4.

In block 1020, the base station determines a need for an update to thesecond persistent allocation for CS4. Such a change may be based on avoice activity detection (VAD), a change in the size of the allocationdue to an updated modulation and coding scheme, a change in the size ofan allocation due to an increased or decreased amount of data to betransmitted over the uplink or a variety of other reasons. For example,block 1020 may correspond to the functions of blocks 410 and 420 on asecond pass through the flowchart shown in FIG. 4.

In block 1030, the base station determines that the start allocation isbetween the allocation for CS3 and CS4. For example, in one aspect, thepersistent UL IE generator 250 determines the start allocation based oninformation received from the group scheduler 240 of FIG. 2,corresponding to the functions in block 440 and 450 of FIG. 4. The startallocation indicates a delineation between a set of previously assigneda persistent allocations and a set of allocations defined by the updatedinformation element. For example, as further illustrated in FIG. 7, thebase station logically moves the start allocation information element topoint to the start of the allocation corresponding to the first clientstation with in the logical map having a change in its allocation. Thebase station issues a persistent allocation information element definingallocations for client station having a allocations logically later thanthe start allocation information element.

In block 1040, the base station sends an updated information elementspecifying a start allocation and a revised allocation for clientstations CS4, CS5, CS6 as well as any non-persistent allocations grantedfor this frame.

Upon receipt of the updated information element, the client stationsCS1, CS2 and CS3 (sometimes called mobile stations, MS) each determinethat the start allocation occurs later in the logical mapping than theircurrent allocation, and thus continue to use the most recently specifiedpersistent allocation.

Upon receipt of the updated information element, client stations CS4,CS5 and CS6 each determine that the start allocation occurs earlier inthe logical mapping than their current allocation, and begin to usepersistent allocation specified in the updated information element.

This method can also be used to efficiently deallocate a persistentallocation. For example, assume that a change to the allocation forclient station CS4 occurred and that the persistent allocation withrespect to client station CS5 has been deallocated, the updatedinformation element sent in block 1040 may include the same startallocation but only a revised allocation for client stations CS4 andCS6. Upon receipt of the updated information element, client station CS5determines that the start allocation occurs earlier in the logicalmapping than its current allocation but that no new allocation wasspecified and, thus, cease transmissions over the previously grantedpersistent allocation. In other aspects, the base station issues anexpress deallocation.

Likewise, this method can also be used to efficiently grant a newpersistent allocation. For example, assume that an initial grant to aclient station CS10 is made and that no other changes are needed for thecurrent frame. The base station creates a revised information elementwhich specifies a start allocation equal to what was previously the endof the persistent allocation region, as well as the new grant. Uponreceipt of the revised information element, every client station with apersistent allocation determines that the start allocation occurs laterin the logical mapping than its current allocation and continues to usethe previously granted persistent allocation. The client station CS10begins to use its new persistent grant.

In one aspect, this functionality is advantageously designed such thatthe base station performs most of the functionality necessary forimplementation. According to this aspect, the client station caches itspersistence allocation and simply refreshes the cache based on the startallocation pointer and any new allocations granted in the revisedinformation element, such as by making use of the UL MAP module 320 andstorage device 324 of FIG. 3. For example, this functionality can beimplemented without the need to use out of band signaling to manage thepersistent allocation region and without the need for the client stationto store information about allocations made to other client stations.Through the use of the start allocation indication, overhead messagingassociated with updating the persistent allocation is reduced incomparison with resending each allocation every time a change occurs.

FIG. 5 is a simplified flowchart of an embodiment of a method 500 ofoperating with persistent uplink resource allocation. The method 500 canbe performed by a client station, such as a client station of FIG. 1 ora client station of FIG. 3.

The method 500 begins at block 510 where the client station receives anuplink MAP that may include one or more persistent uplink informationelements. In one aspects, these functions are performed by the antenna302, the receiver 310 and the UL-mapper module 320 of FIG. 3. The clientstation proceeds to decision block 520 and determines whether there isany persistent uplink information element included within the UL-MAP. Inone aspect, this function is performed by the UL-MAP module 320. If not,the client station proceeds to decision block 530.

At decision block 530, the client station determines whether it has apreviously assigned active persistent uplink allocation. If not, theclient station proceeds to done block 590 and processing is concludedfor the present frame. If, at decision block 530 the client stationdetermines that it has a previously assigned active persistent uplinkallocation, the client station proceeds to decision block 560, which isdescribed below. In one aspect, the function of block 530 is performedby the UL-MAP module 320, the storage device 324 and the UL resourcemapper 330.

If, at decision block 520, the client station determines that apersistent UL allocation information element exists, the client stationproceeds to decision block 540 to determine if any persistent uplinkallocation is directed to the client station. For example, the clientstation determines whether any current persistent resource allocationoccurs logically before or after the point indicated by an uplinkallocation starting point. If the starting point is logically after acurrently active persistent resource allocation, the base station is notchanging the client station's persistent allocation and flow continue toblock 560. In one aspect, the functions of block 540 are performed bythe UL MAP module 320 with reference to the storage device 324.

If, at decision block 540 the client station determines that apersistent uplink allocation is directed to the client station, theclient station proceeds to block 550 to determine the resourcesallocated to the client station. For example, the client stationdetermines that a current persistent resource allocation occurslogically after the point indicated by the uplink allocation startingpoint specified in the information element, thus indicating that thebase station is changing the client station's persistent allocation. Theclient station examines the persistent uplink information element todetermine an express allocation or deallocation contained therein. Inone aspect, these functions are performed by the UL resource mapper 330transmission and UL MAP module 320 with reference to the storage device324. Flow continue to block 560.

In block 560, the client station configures the uplink per the allocatedresources, whether newly or previously granted. The client stationproceeds to block 570 and transmits the uplink signal during theallocated frames and using the allocated resources. In one aspect,functions block 560 and 570 are performed by the uplink resource mapper330, the channelizer 350, the synchronizer 360, the transmitter 370, andthe antenna 302 of FIG. 3.

FIG. 6 is a simplified embodiment of an uplink frame 600 having a firstportion of resources 620 within the frame 600 having persistentallocation and a second portion of resources 630 within the frame 600having persistent and non-persistent allocation. The frame 600 mayinclude one or more portions, e.g. 610, that are configured to carryoverhead information, acknowledgement messages, random access channelrequests, or other information that is transmitted without an expressresource allocation.

The frame 600 can be interpreted as illustrating two-dimensions overwhich resources can be allocated. For example, the horizontal scale canrepresent time and the vertical scale can represent frequency. Thus,each block can represent an allocation unit. For example, each blockwithin the frame 600 can represent a slot having a predetermined numberof symbol periods and a predetermined number of subcarriers.

An UL Allocation Start IE 640 can be configured, for example, as apointer in the UL-MAP that identifies the boundary between allocationsdefined in one or more previous frames and allocations defined in thisframe. For example in this case, the first portion of resources 620includes assigned persistent allocation defined in previous UL MAPS forthe client stations CS1, CS1, CS3 and CS4. The second portion of theresource is 630 includes persistent and nonpersistent allocationsassigned in the current UL MAP, such as the persistent allocationsassigned to CS5, CS6 and CS7.

FIG. 7 is a simplified representation of a logical mapping of an uplinkresource allocation. The representation of FIG. 7 illustrates a portionof the UL frame as a single ribbon having a width equal to a width of anallocation unit. The frame portion illustrated in FIG. 7 shows thetransition from the persistent allocated resources allocated to theclient stations CS1, CS2, CS3, and CS4 to the persistent ornon-persistent resources allocated to client stations CS5 and CS6. TheUL Allocation Start IE points to the end of the last persistent resourceallocation defined in a previous frame and the first allocation, whetherpersistent or non-persistent, which is defined in this frame.

As can be seen by comparing FIG. 6 to FIG. 7, the single ribbon shown inFIG. 7 is a logical mapping of a frame such as the one shown in FIG. 6.The logical mapping defines an identified ordering which is known byboth the base station and the client stations. However, the identifiedordering need not, and typically does not, occur in sequential time orfrequency order. For example, if we assume in FIG. 6 that the horizontalaxis is time and the vertical axis is frequency, the client stationsCS1, CS3, CS4, CS6 and CS7 all transmit during the second time slot. Inmany systems, the allocation units assigned to a single client stationare spread throughout the uplink frame rather than in a localized regionas shown in FIG. 6. Because the base station and client stations areeach aware of the logical mapping used in the system, the uplinkallocation start information element can be used to specify any point inthe logical mapping before which allocations were defined in a previousframe and after which allocations are defined in this frame, regardlessof the actual timing of transmissions made by the client stations.

FIG. 8A is a simplified embodiment of uplink frames illustrating partialpersistent resource reallocation. The first frame in FIG. 8A illustratesa resource allocation for a particular frame in time. The second framein FIG. 8A illustrates a partial resource allocation, where one or morepersistent or non-persistent allocated resources are modified, added,deleted, or otherwise updated. The region of persistent resourcesallocated in prior UL-MAPS that is not updated need not be communicatedagain in the present UL-MAP. The UL Allocation Start IE points to thebeginning of the changes in resource allocation.

FIG. 8B illustrates uplink frames with partial persistent resourceallocation. A first frame shows persistent resources that were allocatedin a prior UL-MAP. The UL Allocation Start IE points to the boundarybetween the region defined in this uplink MAP and the region defined inprevious uplink MAPs. The UL-MAP for the present frame likely does notinclude any persistent resource allocation.

The second frame illustrates a partial change in persistent resourceallocation at some later frame. The UL Allocation Start IE points to thebeginning of the changed resources. Thus, in one aspect the ULAllocation Start IE is used to delineate between a ‘region’ of the ULframe, which has been defined in previous UL MAPs (sticky) and a‘region’ of the UL frame defined in this UL MAP (can be both sticky andnon-sticky). Note that the persistent resource allocation for clientstations CS1 and CS2 do not change. The UL-MAP for this frame need notinclude any express resource grant for those client stations, as theycontinue to utilize the persistent resources previously allocated tothem. The persistent resources for client stations CS3, CS4, and CS5 maybe different. Typically, at least the resource allocation to clientstation CS3 is different, thus triggering the update of resourcesallocated to client stations CS4 and CS5.

If a client station requires a change to its persistent allocation, allclient stations having an allocation which are later in the logicalmapping are typically granted a new allocation. Therefore, there is moreoverhead associated with making a change to a persistent allocationwhich is toward the beginning in the logical map rather than towards theend of the logical map. In one aspect of the invention, the base stationsorts the allocation grants within the logical mapping according to theprobability that the client station will require a change to itspersistent allocation.

For example, a client station which is moving rapidly is more likely tochange its modulation and coding scheme than a client station which isstationary. Therefore it may be advantageous for fast-moving clientstations to have allocations towards the end of the logical mapping.Thus, a mobility factor can be used, at least in part, to determine arate of change factor for each client station.

Likewise a client station with degraded wireless link performance ismore likely to require a change to its modulation and coding scheme.Thus, a link performance parameter (such as, signal to noise ratio,packet or bit error rate, carrier to noise ratio, energy per bit dividedby noise power density etc.) may be used, at least in part, to determinea rate of change factor for each client station. In addition, some typesof links are more likely to experience a need for a change in apersistent allocation and, thus, the type of connection may be used, atleast in part, determine a rate of change factor. For example, a VoIPconnection may experience frequency voice activity masks and, therefore,have a high rate of change factor.

FIG. 9 is a simplified flowchart of an aspect of a method 900 ofefficiently assigning a persistent resource allocation. In block 910,the base station identifies one or more client stations for which it isgoing to grant an original or updated persistent allocation. The basestation determines a rate of change factor for each of the clientstations in block 920. In block 930, the base station determines alogical order based at least in part on the rate of change factor. Forexample, the base station schedules the allocations within a logicalmapping so that client stations with a lower rate of change factor arescheduled logically before client stations with a higher rate of changefactor.

In one aspect, if the client station misses receiving an updatedpersistent map information element, it is unable to decode the uplinkpersistent map, which can lead to a the client station getting out ofsync with respect to its persistent allocation assigned to it by thebase station. In one aspect, the client station should not transmit ifit detects a loss of frame in which it may have had a persistentallocation. In another aspect, the base station may provide periodic MAPrefresh specifying all active persistent allocations to address any syncproblems which may have occurred. In another aspect, the base stationdetects that a client station is potentially out of sync by monitoringthe client station transmission in the uplink, which the base stationdoes anyway in typical implementations. If the client station does nottransmit in the designated persistent allocation, the base station canconsider that this is an indication that the client station hasexperienced a lost frame event and can issue a MAP refresh.

Thus, among other things, described herein are methods and apparatusesfor efficiently assigning persistent resources. In one aspect, when atleast one persistent allocations is made or updated, the base stationsends an information element to a set of client stations. Theinformation element includes a start allocation and a list of expressgrants of persistent allocations. The start allocation indicates adelineation between a set of previously assigned persistent allocationsand a set of persistent and/or non-persistent allocations defined by thecurrent information element. When received by a client station, theclient station compares the start allocation with the starting point ofits current persistent allocation. If the starting point is logicallybefore the start allocation, the client station continues to operateaccording to the previously assigned persistent allocation. If itsstarting point is logically after the start allocation, the clientstation begins to operate according any grant included within thecurrent information element. In one aspect, the base station assignsresources to the client stations in a logical order based upon theprobability that the client station will incur an update to itspersistent allocation.

In some embodiments, a client station's persistent allocation may bedeallocated or temporarily deactivated. In addition, its persistentallocation may be changed such as due to the deallocation ordeactivation of a persistent allocation of another client station'sresource allocation.

The client station that is deallocated or temporarily deactivated simplyceases transmitting on its allocation. In one aspect, a client stationhaving a persistent allocation which occurs logically after thedeallocated/deactivated allocation determines a new persistentallocation. For example, the client station can determine the magnitudeof the change, in terms of the number of vacated allocation units, basedon the magnitude of the persistent allocation which has been deallocatedor deactivated. The client station can shift its resource allocationaccording to the size of the temporarily deactivated resourceallocation.

For example, the base station transmits mask information as part ofgranting persistent allocations. Such masks are often used in order tosupport VAD (voice activity detection) in the client station. VAD can beused by voice codec to suppress VoIP packet generation when the user issilent. The Mask field can be a bit mask used to indicate that certainusers in the persistent allocation array are silent and thus do not havean allocation in the persistent array until next update.

In one aspect, a mask is used to support the efficient deallocation ofpersistent resources. Users previously provided a persistent resourceallocation can simply shift in accordance with the bit value (0/1) tocompress the allocations to utilize the resource released by the clientstations that are marked with zero value. The advantage of using theMask instead of simply making an update to the persistent allocationarray is that it will cost less overhead.

Because the base station may update a subset of the persistent resourceallocation without sending out the entire persistent resource allocationinformation, the base station may track a presumed client stationknowledge of the entire persistent allocation information. The basestation may only need to track this presumed knowledge until the entirepersistent resource allocation information is refreshed or otherwiserebroadcast.

The base station can also include information in the persistent uplinkresource allocation information element that identifies a deallocationor temporary deactivation of a previously allocated persistent uplinkresource. The deallocation of resources for a particular client stationmay be temporary and the resources may be re-allocated to the sameclient station. Alternatively, if the client station has completedtransmissions or otherwise dropped the communication link, thedeallocation may temporarily indicate the absence of resources allocatedto the client station until the complete persistent resource allocationinformation is refreshed.

FIG. 11 is a simplified diagram showing a series of persistentallocation regions of a downlink frame and illustrating use of a mask.The persistent allocation region includes allocations for five clientstations (CS1-CS5) which are currently assigned in numerical order tosub-burst 1 to sub-burst 5. A logical map 1120 shows the correspondinglogical mapping in a single ribbon format, similar to the logicalmapping shown in FIG. 7. In one aspect, the base station uses a mask todeallocate/deactivate previously granted persistent allocations. Theposition of the bit within the mask represents the position of thesub-burst within the persistent allocation region. The value of the bitindicates whether a client station should cease using a previouslyassigned persistent allocation.

By way of example, assume that the base station would like to deallocatethe persistent allocation corresponding to client station number 3. Itsends a mask which indicates which allocations are remaining allocatedand which allocations have been deallocated/deactivated. Thus, todeallocate client station 3, the base station sends a mask as follows:(1,1,0,1,1). The leading two 1's indicate that the persistentallocations granted to client stations 1 and 2 have not beendeallocated. The zero indicates that client station 3 should ceasetransmission on the previously assigned persistent allocation. And, thelast two 1's indicate that the persistent allocations granted to clientstations 4 and 5 have not been deallocated. In response, each clientstation with an allocation which occurs logically after the allocationassigned to client station 3 shifts its allocation logically earlier bythe magnitude of the persistent allocation formerly assigned to clientstation 3.

Thus, in the frame in which the deallocation becomes effective, alogical ribbon 1130 shows the resulting allocations. Namely, sub-bursts1 and 2 remain unchanged. Sub-burst 3 now carries downlink data forclient station 4 and is the size of the allocation assigned to clientstation 4. Sub-burst 4 carries downlink data for client station 5 and isthe size of the allocation assigned to client station 5. The persistentallocation region 1140 shows the resulting downlink frame based on thelogical ribbon 1130. Note that it is possible to deallocate severalpersistent allocations in one mask by setting the corresponding bitpositions to zero.

According to the aspect just described, client stations 4 and 5 mustknow the size of the allocation assigned to client station 3 so thatthey can shift their allocations earlier by the proper amount. In oneaspect, each client station stores an indication of the size of eachallocation which occurs logically before its own. Such information canbe determined by monitoring the downlink map IE, both in terms ofinitial grants and deallocations/deactivations indicated by the masks.

In another aspect, the mask includes information about the size of thedeallocated/deactivated allocations. For example, the base station sendsa mask as follows: (1, 1, 0, 1, 1: 4) indicating that the client stationnumber 3 has been deallocated and that its allocation was 4 allocationunits in magnitude. If more than one allocation/deactivation occurs inone frame, the base station sends a mask as follows: (1, 1, 0, 0, 1: 4,6), thus indicating that both the client station 3 and client station 4have been deallocated and that client station 3's allocation was 4allocation units in magnitude and client station 4's allocation was 6allocation units in magnitude.

FIG. 12 is a simplified flowchart of an aspect of a method 1200 ofdeallocating a persistent resource allocation from the perspective of abase station. In block 1210, the base station sends one or more IEsgranting persistent allocations, such as to client stations 1-5. In oneaspect, a transmitter similar to the transmitter 370 of FIG. 2 performsthis function. Again, for ease of explanation, we assume that thepersistent allocations occur in numerical order in the logical mapping.In block 1220, the base station determines a need to deallocate clientstation 3. In one aspect, a persistent candidate processor similar tothe persistent candidate processor 230 of FIG. 2 performs this function.In block 1230, the base station sends a mask which may include anindication of the size of the persistent allocation formally granted toclient station 3. In one aspect, the mask is developed in a groupscheduler similar to group scheduler 240 of FIG. 2.

FIG. 13 is a simplified flowchart of an aspect of a method 1300 ofdeallocating a persistent allocation resource from the perspective of aclient station. In block 1310, the client station receives one or morelEs granting persistent allocations, such as to client stations 1-5. Forexample, the client station may receive the IE's using a receiversimilar to receiver 310 of FIG. 3. Again, for ease of explanation, weassume that the persistent allocations occur in numerical order in thelogical mapping. In block 1320, the client station stores informationregarding its current logical position within the persistent allocationregion. In one aspect, the client station also stores an indication ofthe size of persistent allocations occurring logically before itspersistent allocation. For example, such information may be stored inmemory such as the storage device 324 shown in FIG. 3. In block 1330,the client station receives a mask indicating that one or morepersistent allocations has been deallocated/deactivated. In one aspect,the mask also includes an indication of the size of anydeallocated/deactivated persistent allocations. In block 1340, theclient station determines a new persistent allocation if thedeallocated/deactivated persistent allocations occur logically beforeits persistent allocation. For example, the client station shifts itsallocation logically earlier by the sum of the magnitude of persistentallocations that have been deallocated and that occur logically earlierthan its own using control logic similar to the resource mapper 330shown in FIG. 3.

Although FIGS. 11, 12 and 13 illustrate were described with respect todownlink persistent allocations, the illustrated principles may bereadily applied to the uplink.

As used herein, the term coupled or connected is used to mean anindirect coupling as well as a direct coupling or connection. Where twoor more blocks, modules, devices, or apparatus are coupled, there may beone or more intervening blocks between the two coupled blocks.

The steps of a method, process, or algorithm described in connectionwith the embodiments disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. The various steps or acts in a method or processmay be performed in the order shown, or may be performed in anotherorder. Additionally, one or more process or method steps may be omittedor one or more process or method steps may be added to the methods andprocesses. An additional step, block, or action may be added in thebeginning, end, or intervening existing elements of the methods andprocesses.

The above description of the disclosed embodiments is provided to enableany person of ordinary skill in the art to make or use the disclosure.Various modifications to these embodiments will be readily apparent tothose of ordinary skill in the art, and the generic principles definedherein may be applied to other embodiments without departing from thescope of the disclosure.

1. A method of receiving a persistent allocation, comprising: receivinga first information element specifying a first persistent allocationoccurring at a fixed point with an a logical mapping; receiving a secondinformation element including a mask; and continuing to operateaccording to the first persistent allocation if the mask indicates thatthe first persistent allocation has not been deallocated and that nopersistent allocation occurring logically earlier than the firstpersistent allocation has been deallocated.
 2. The method of claim 1,wherein the second information element includes an indication of themagnitude of a deallocated persistent allocation.
 3. The method of claim1, further comprising: determining a new persistent allocation if asecond persistent allocation occurring logically earlier than the firstpersistent allocation has been deallocated; and determining shifts thefirst persistent allocation logically earlier according to a magnitudeof the second persistent allocation.
 4. The method of claim 3, whereinthe second information element specifies the magnitude of the secondpersistent allocation.
 5. A method of efficiently assigning persistentresources, comprising: sending one or more information elementsspecifying a first, second and third persistent allocation for a first,second and third client station respectively, wherein the first, secondand third persistent allocations occur in numerical order in a logicalmapping; and sending a subsequent information element including a maskto commanding the second client station cease operation on the secondpersistent allocation.
 6. The method of claim 5, further comprisingincluding within the subsequent information element an indication of themagnitude of the second persistent allocation.
 7. A base station thatefficiently assigns persistent resources, comprising: means for sendingone or more information elements specifying a first, second and thirdpersistent allocation for a first, second and third client stationrespectively, wherein the first, second and third persistent allocationsoccur in numerical order in a logical mapping; and means for sending asubsequent information element using a mask to commanding that thesecond client station cease operation on the second persistentallocation.
 8. The base station of claim 7, further comprising means forincluding within the subsequent information element an indication of themagnitude of the second persistent allocation.
 9. A machine readablemedium containing executable computer program instructions which whenexecuted by a digital processing system cause the system to perform amethod of resource allocation, comprising: sending one or moreinformation elements specifying a first, second and third persistentallocation for a first, second and third client station respectively,wherein the first, second and third persistent allocations occur innumerical order in a logical mapping; and sending a subsequentinformation element using a mask to commanding that the second clientstation cease operation on the second persistent allocation.
 10. Aclient station that receives a persistent allocation, comprising: meansfor receiving a first information element specifying a first persistentallocation occurring at a fixed point with an a logical mapping; meansfor receiving a second information element including a mask; and meansfor continuing to operate according to the first persistent allocationif the mask indicates that the first persistent allocation has not beendeallocated and that no persistent allocation occurring logicallyearlier than the first persistent allocation has been deallocated. 11.The client station of claim 10, wherein the second information elementincludes an indication of the magnitude of a deallocated persistentallocation.
 12. The client station of claim 10, further comprising meansfor determining a new persistent allocation if a second persistentallocation occurring logically earlier than the first persistentallocation has been deallocated and wherein the means for determiningshifts the first persistent allocation logically earlier according to amagnitude of the second persistent allocation.
 13. The client station ofclaim 12, wherein the second information element specifies the magnitudeof the second persistent allocation.
 14. A machine readable mediumcontaining executable computer program instructions which when executedby a digital processing system cause the system to perform a method ofassigning resources, the method comprising: receiving a firstinformation element specifying a first persistent allocation occurringat a fixed point with an a logical mapping; receiving a secondinformation element including a mask; and continuing to operateaccording to the first persistent allocation if the mask indicates thatthe first persistent allocation has not been deallocated and that nopersistent allocation occurring logically earlier than the firstpersistent allocation has been deallocated.
 15. A method of efficientlyassigning persistent resources, the method comprising: sending one ormore information elements specifying a first, second and thirdpersistent allocation for a first, second and third client stationrespectively, wherein the first, second and third persistent allocationsoccur in numerical order in a logical mapping; determining a need for anupdate to the second persistent allocation; and sending a subsequentinformation element specifying a start location and a revised second andthird allocation, wherein the start allocation indicates a delineationwith the logical mapping between a set of previously assignedallocations and a set of allocations defined by the subsequentinformation element.
 16. A method of receiving a persistent allocation,the method comprising: receiving a first information element specifyinga first persistent allocation occurring at a fixed point with an alogical mapping; receiving a second information element specifying astart allocation indicating a change point within the logical mapping;and continuing to operate according to the first persistent allocationif the fixed point occurs logically before the change point.
 17. Themethod of claim 16, further comprising operating according to a newlyspecified persistent allocation as indicated in the second informationelement if the fixed point occurs logically after the change point. 18.The method of claim 16, further comprising ceasing to operate accordingto the first persistent allocation if the fixed point occurs logicallyafter the change point and no new persistent allocation is includedwithin the second information element.
 19. A communications unit thatassigns persistent resources, comprising: means for sending one or moreinformation elements specifying a first, second and third persistentallocation for a first, second and third client station respectively,wherein the first, second and third persistent allocations occur innumerical order in a logical mapping; means for determining a need foran update to the second persistent allocation; and means for sending asubsequent information element specifying a start location and a revisedsecond and third allocation, wherein the start allocation indicates adelineation with the logical mapping between a set of previouslyassigned allocations and a set of allocations defined by the subsequentinformation element.
 20. A communications unit that receives apersistent allocation, comprising: means for receiving a firstinformation element specifying a first persistent allocation occurringat a fixed point with an a logical mapping; means for receiving a secondinformation element specifying a start allocation indicating a changepoint within the logical mapping; and means for continuing to operateaccording to the first persistent allocation if the fixed point occurslogically before the change point.